In a medium bowl combine butter and shortening; beat with an electric mixer on medium to high speed for 30 seconds. Add sugar, baking powder, and salt. Beat until combined, scraping sides of bowl occasionally. Beat in egg and vanilla until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. Cover; chill about 1 hour or until dough is easy to handle.

Preheat oven to 375 degrees F. Divide dough into thirds. On a lightly floured surface, roll dough one portion at a time to 1/4-inch thickness. Cut dough using 2-1/2- to 5-inch star-shape cutters. Place star cutouts on an ungreased cookie sheet.

Bake for 8 to 10 minutes or until edges are firm and bottoms are very lightly browned. Cool on cookie sheet for 1 minute. Transfer cookies to wire racks; let cool.

Frost and pipe cookies with Royal Icing Glaze as desired. If desired, sprinkle with sanding sugar or use a tiny clean paintbrush to paint the piped designs with Luster Dust Topper. Makes about 48 (2-1/2-inch) cookies or about 16 (5-inch) cookies.

Royal Icing Glaze: In a small bowl combine 2 cups sifted powdered sugar, 4 teaspoons meringue powder,* and 1/4 teaspoon cream of tartar. Stir in 1/4 cup warm water. Beat with an electric mixer on low speed until combined, then on high speed for 7 to 10 minutes or until very stiff. Add 1 to 2 tablespoons additional warm water 1 teaspoon at a time until icing is of glazing consistency.

Luster Dust Topper: Place 1/2 teaspoon gold, silver, or pearl luster dust in a custard cup.** Stir in 2 teaspoons vodka. (The vodka will evaporate, leaving a dry mixture that you can easily paint onto icing.)

To Store: Place in layers separated by waxed paper in an airtight container; cover. Store at room temperature for up to 3 days. (Or freeze undecorated cookies for up to 3 months. Thaw, then decorate cookies.)

*Note: Merigue powder is a mixture of pasteurized egg whites, sugar, and edible gums. Look for it in the baking aisle of your supermarket or at a specialty food store.

**Note: Look for luster dust in the cake and cookie decorating department of a hobby store.